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Message-ID: <1274280257.26328.767.camel@gandalf.stny.rr.com>
Date: Wed, 19 May 2010 10:44:17 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Frederic Weisbecker <fweisbec@...il.com>
Cc: Johannes Berg <johannes@...solutions.net>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: collecting static data related to tracing
On Wed, 2010-05-19 at 09:28 +0200, Frederic Weisbecker wrote:
> On Tue, May 18, 2010 at 04:45:09PM +0200, Johannes Berg wrote:
> This is a place where events injection might be suitable perhaps.
> Either kernel or user space event injection.
>
> kernel space injection would be a simple trace event declared that
> have a callback called when it gets enabled. This callback would
> inject any events it wants.
>
> userspace injection could be a bit different, the user can inject
> its own format and events content toward a debugfs or whatever file.
> This would be suitable if userspace have few things to inject,
> otherwise we would need to think about something else perhaps.
>
The userspace injection actually sounds like a good idea. I don't think
it needs to tell the kernel about it. Since it is running the trace.
Perhaps just have a way that the userspace can add its own events to the
recording file.
I guess this would be closer to what LTTng does with channels.
That is, you could have a separate recording stream to write events that
tell the tracer what is happening. It would be nice to have a way that
userspace can read the trace clock timer though.
-- Steve
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